Mechanical pole climber



P 7, 1970 D. c. SHERMAN 3,504,767

MECHANICAL POLE CLIMBER Filed July 15, 1968 5 Sheets-Sheet 1 INVENTOR. DELMAR c. SHERMAN A TTO/Q/VEYS April 7, 1970 D. c. SHERMAN 3,504,767

\ MECHANICAL POLE CLIMBER Filed July 15, 1968 5 Sheets-Sheet 2 00 IN VENTOR. /2o DELMAR c. SHERMAN ATTORNEYS April 7, 1970 D. c. SHERMAN MECHANICAL POLE CLIMBER 5 Sheets-Sheet 5 Filed July 15, 1968 mum M Wm wmmww M P "H MEA E D m W April 7, 1970 D. c. SHERMAN MECHANICAL POLE CLIMBER 5 Sheets-Sheet 4 Filed July 15, 1968 DELMAR c. SHERMAN ATTORNEYS April 1970 D. c. SHERMAN 3,504,767

MECHANICAL POLE CLIMBER Filed July 15, 1968 5 Sheets-Sheet 5 INVENTOR DEL/MAR G SHERMAN A 7' TOR/V575 United States Patent O 3,504,767 MECHANICAL POLE CLIMBER Delmar C. Sherman, Chattanooga, T enn., assignor to Sherman & Reilly, Inc., Chattanooga, Tenn., a corporation of Tennessee Filed July 15, 1968, Ser. No. 745,339 Int. Cl. A63b 27/00; E04g 3/00 US. Cl. 182136 10 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates generally to a climbing vehicle, and more particularly, to a portable machine capable of climbing tapered and obstructed poles.

In the past, linemen have traditionally climbed wooden poles either by means of spikes strapped to the feet or by steps extending outward from the pole. The use of steps 'has always been undesirable because unauthorized persons, even children, can then climb up the pole. Furthermore, the steps provide additional hazard for a lineman because of interference with the linemans safety belt.

In recent years the traditional wooden pole has been supplanted with concrete and steel poles and by poles of much greater height. Obviously, the steel and concrete poles cannot be climbed with the traditional spikes. The undesirability or" steps remains. Finally, the increased height requires an expenditure of a great deal of a linemans energy during his daily routine. It is, of course, desirable that the linemans strength and energy be conserved for his tasks at the top of the pole.

An additional difficulty is the obstacles presented by the various support guy wires, brackets, and various lines spaced at distances below the primary line near the top of the pole. What is required then, is a device that is not too heavy and bulky and yet capable of carrying a lineman, his tools, and supplies, quickly and conveniently, up a pole and by various obstructions.

SUMMARY OF THE INVENTION Therefore, to overcome the foregoing and other difficulties of the prior art, it is the general object of this invention to provide a new and improved device capable of climbing a pole and bypassing obstructions thereon while carrying a lineman, his tools and supplies. To this end, the mechanical pole climber of the invention is envisioned as having a generally vertical load-supporting frame with a drive means mounted thereon. At least three clamping arms are pivoted at spaced positions on the frame so that any one of the arms may be pivoted outward to clear an obstruction while the remaining two arms maintain the climber in engagement with the pole. Each of the arms normally is embraced about the pole and has a capability of expanding and contracting. A friction traction means is engaged against the pole to receive power from the drive means for moving the climber up and down the pole. Simultaneously, a clamping means receives power from the drive means for expanding and contracting the arms about the pole, according to the taper thereof. A manually operable control 3,504,767 Patented Apr. 7, 1970 engages the drive means for up or down travel and is biased to a central brake position.

Thus, one of the objects of this invention is to provide ease, efiiciency and safety in climbing the tall modern pole.

It is an object of this invention to conserve the energy of linemen by providing a mechanical pole climber.

Another object of this invention is to provide a pole climbing machine which readily bypasses obstructions.

It is still another object to provide a pole climbing machine which automatically accommodates for pole taper.

Another object of this invention is to provide a pole climbing machine which is safe and dependable, having a manual control which is normally biased to a braking position.

Yet another object is to provide a pole climbing machine which is readily portable, light weight and compact, and yet capable of dependably carrying a lineman, his tools and supplies, up a pole and by various obstructions thereon.

Yet another object is to provide a pole climbing machine which is economical to produce by utilizing a minimum of conventional, currently available components and materials that lend themselves to standard massproduction manufacturing techniques.

Further and other objects, and a more complete understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS For the purpose of illustrating the invention, there is shown in the drawings, a form which is presently preferred, it being understood, however, that this invention is not necessarily limited to the precise arrangements and instrumentalities there shown.

FIG. 1 is a perspective view of the invented pole climber, shown on a pole and in the process of by-passing an obstruction thereon;

FIG. 2 is an enlarged plan view showing the details of a clamping arm of the invention about a typical metal pole cross-section;

FIG. 3 is an end view in the directions of arrows 3-3 in FIG. 2;

FIG. 4 is a cross-section taken along line 44 of FIG. 2;

FIG. 5 is an elevational view partially in section, taken in the direction of arrows 55 of FIG. 2, showing a traction drive unit of the invention;

FIG. 6 is a cross-section taken along line 66 of FIG. 6;

FIG. 7 is an enlarged section taken along line 7-7 of FIG. 2, showing a cross-slide connective and clamping drive:

FIG. 8 is a broken and partially sectioned side elevation of the support frame, control, and drive means of the invention:

FIG. 9 is an end view looking in the direction of arrows 99 of FIG. 8;

FIG. 10 is an end view, partially in section, in the direction of arrows 10-10 of FIG. 8;

FIGS. 11 and 12 are enlargements of FIG. 10, showing alternate positions of the control linkage.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail, wherein like numerals indicate like elements, there is shown in FIG. 1 a mechanical climber of the present invention, designated generally by the numeral 10. FIG. 1 is a typical illustration of the mechanical climber 10 climbing a pole 20 (in phantom) and the process of by-passing an obstruction provided by wire (in phantom) pending from the pole.

With reference to the detail of FIG. 8, a load-supporting frame may be provided by a vertical member 30, support clamps 33, and a platform member 35. Vertical member 30, the frame backbone, is preferably a durable, high-strength metal section. In the embodiment illustrated, vertical member is provided by a cold drawn seamless steel tubing of a square section, as indi cated best at FIG. 9. The support clamps 33 may be durable metal castings having a flat base portion 32 and a projecting collar portion 34, as shown in FIGS. 8 and 9. The support clamps 33 are lace in pairs on opposite sides of the vertical member 30 at the positions shown. Fasteners 37, common nuts and bolts, pass through base portion 32 of each pair, on opposite sides of the vertical member 30, as indicated in FIG. 9. Tightening of the fasteners 37, of course, secures the support clamps 33 in position.

Drive means are mounted on the support frame and may be provided by a variety of suitable power sources, for example, an electric motor, an internal combustion engine, or even a foot or hand operated drive system. Preferably, however, a lightweight and portable gasoline engine (visible in FIG. 8), of the type commonly used for portable tools is utilized. Engine 40 is secured on a suitable mounting bracket 42 by means of nut and bolt fasteners 43. A drive pulley 44 is appropriately keyed to the output shaft of the engine 40. Note that the drive pulley 44, which may be an integral casting, has a projecting friction drive portion 45 and a sheave portion 46 for respective engagement with sheaves 47, 48 keyed to a vertical worm drive shaft 50. A common V-belt S1 completes the engagement between sheaves 46 and 48 in the manner indicated. As will be described more completely hereafter, provision is made for support bracket 42 to pivot for movement of engine 40 and drive pu ley 44 to and from sheaves 47, 48 of worm drive shaft 50. In this manner, it is understood that there will be an alternate engagement of the projecting friction drive 45 with sheave 47 and of the sheaves 46-48 via pulley 51. In this manner, the one-way rotation provided by engine 40 is utilized to provide forward and reverse rotation at the vertical worm drive shaft 50.

As may be best visualized with reference to FIG. 1, the vertical worm drive shaft 50 passes through three worm gear housings and is journaled for rotation therein. The housings 55 are supported on member 30 by means of support clamps 33. With reference to the detail of FIG. 5, it is seen that shaft 50 rotates a worn 56 in each housing 55 to drive a worm gear 58. The worm gear 58 is journaled in housing 55 on a horizontally disposed shaft 59, an end of which extends outward from the housing 55 and is visible in FIG. 5. Driving power of shaft 59 is utilized for purposes to be described hereafter.

A plurality of supporting means, numbering three in the illustrated embodiment shown in FIG. 1 are mounted on the support frame vertical member 30 for independent movements relative thereto. That is, partially U-shaped arms 60, though mounted to rigidly extend at horizontal dispositions from housings 55, are free to pivot along with housings 55 on shaft 50, outward, in the direction of the arrow, away from pole 20. The arms 60 are sufficiently spaced apart so that any two are able to maintain the climber 10 on pole 20 while one arm 60 is disengaged, as demonstrated by FIG. 1. Each of the arms 60 is formed by separate lengths 61, 62 and 63, joined together by crossslide members 65. 'It is understood that the individual lengths 61, 62, 63 are 'slidable within cross-slide member 65, and with respect to one another, enabling the partially U-shaped arm member 60 to contract and expand according to the cross-section of pole 20. Cross-slides 65, as shown in FIGS. 1, 2, 3, 4, 7, are preferably sections of cold drawn tubing welded together and long enough to maintain lengths 61, 62, 63 at rigid perpendicular dispositions. Reinforcement plates 66 are welded at the inside corner of each cross-slide 65, as shown. Arm length 61, as may be seen best with reference to FIG. 2, is securely attached to the housing 55 between integral lugs 67, 68 of the housing. Fastening of arm 61 may be accomplished by welding, by fasteners such as machine screws, and/or by another suitable means. A gusset plate 69 welded to the bottom of the tube 61 and to the face of housing 55, provides additional bracing to maintain the length 61 at the horizontal disposition shown.

Traction means, powered from worm gear shaft 59, are provided to engage pole 20 and move climber 10 up and down. The outward extension of worm gear shaft 59 carries two sheaves 70, 71 keyed for rotation thereby. Only outermost sheave 70 is visible in FIG. 5. The innermost sheave 71 (visible in FIG. 2) drives a V-belt 73 which travels a path between guide wheels 74 and over traction sheaves 75. The guide wheels 74 are carried on a Y-shaped adjusting frame 76 which is mounted on the housing 55 by means of a pin 77. Adjustment of the drive belt 73 is readily accomplished by loosening or tightening nuts 78 and movement of the guide wheels 74 to appropriate positions within slots 79 of adjusting frame 76. The pin 77 is journal as indicated by the cross-section of FIG. 6, for rotation in the housing 55 and carries an eccentric shaft 80 which extends outward beyond the adjusting frame 76. A traction drive frame is carried on the eccentric shaft 80. The traction sheaves 75 are journaled on each end of the traction drive frame 85 on shafts 86 as shown. A handle 88 is keyed to the eccentric shaft by means of a spring 89. It may be readily appreciated that eccentric shaft 80 may be rotated by means of handle 88 to cause movement of the traction sheaves 75 and V-belts 73 inward and outward, relative to the pole 20, by virtue of the eccentric movement of the shaft 80 with respect to the axis of pin 77. Further, traction drive frame 85 is free to pivot on eccentric shaft 80, allowing the portion of V-belt 73 between the traction sheave 75 to bear fiat against the pole 20, assuming the taper thereof.

The supporting means provided by arms 60 include clamping means, also powered from worm gear shaft 59, in order to maintain driving engagement of V-belts 73 with pole 20. That is, as illustrated in FIGS. 1 and 2, the arms 60 clamp about the cross-section of pole 20.

Clamping action is provided by operation of take-up screws 91, 92, 93 one for each length 61, 62, 63. Each of the take-up screws 91, 92, 93, has a spline keyway therealong and is journaled in a parallel disposition with its respective arm length. Take-up screw 91 is journaled on length 61 between a bronze nut and bronze gear box 102. Take-up screw 92 is journaled on length 62 between bronze gear box 102, intermediate tangs 105, and bronze gear box 107. Take-up screw 93 is journaled between bronze gear rack box 107 and end tangs 110.

Particular reference is made to the cross-sectional detail of FIG. 7, in regard to bronze gear box 107, which also typifies gear box 102. Each box 102, 107, is a two-part casting bolted together by fasteners 103. Both gear boxes 102, 107 are secured by nut and bolt fasteners 108 to the reinforced plates 66 at the inside corner of cross-slides 65. Each bronze gear box 102, 107 contains a pair of hardened steel 45 helical gears 106, bored for reception of respective take-up screws 91, 92, 93. A keyway in each gear 106 is aligned with spline keyway 95 of respective screws 91, 92, 93 for reception of a key 115. This assures rotation of each helical gear 106 along with its respective screw 91, 92, 93, yet allows longitudinal movement of each screw along with lengths of the arms 60. As shown in FIG. 7, a threaded bore through each gear box 102, 107 receives respective screws 91, 92, 93 and serves as a nut therefor. In this manner rotation of screws 91, 92, 93 screw them in or out of respective gear boxes 102, 107. At the same time, drive rotation is transmitted through gears 106 from screw 91 to screw 92 to screw 93, by virtue of spline keyways 95 and keys 115.

The take-up screw 91 has oppositely threaded portions, from each end to the middle, as shown in FIG. 2. One portion is received within the gear box 102, as previously described. The remaining portion is received within bronze nut 100, which is secured to a flange 116 on length 61 by fasteners 117. As shown by the dashed lines of FIG. 2 and the cross-section of FIG. 4, one end of screw 91 extends outward beyond nut and is received by a hollow quill 120 which is fitted with an internal square key engaged with the spline keyway 95. The quill 120 extends over the worm gear case 55 where it is journaled in bushing 127 contained in the boss 128 cast integrally with lug 68. An adjustable variable pitch sheave 130 is secured to quill 100 by a key 135. A portion of quill 100 extends beyond sheave 130 and is notched at to accept a crank (not shown).

Take-up screw 92 also has oppositely threaded portions from each end to an unthreaded mid-portion 145. The threaded portions are engaged in gear boxes 102, 107 while unthreaded mid-portion is journaled in intermediate tangs 105 on length 62. A roller is journaled between the mid-tangs on the unthreaded mid-portion 145, as indicated.

Take-up screw 93, is somewhat shorter, corresponding to companion arm length 63. Screw 93 has a single threaded portion and a short unthreaded end portion 155. The threaded portion is engaged in gear box 107 while unthreaded end portion is journaled in the end tangs 110 on length 63. A roller 150 is journaled on end portion 155 between end tangs 110.

A quarter twist V-belt connects the adjustable variable pitch sheaves 70, 130 that are on the worm gear shaft 59 and quill 120 respectively. It is understood that the sheaves 70, 130, are of the type which may be adjusted to change the drive speed of take-up screws 91, 92, 93. In this manner, a transmission means is provided for the clamping means enabling it to be adjusted to the rate of climb or descent of the climber 10.

A manually operable control means selectively operates the drive means to cause the climber 10 to either go up, down, or stop, and will be described with reference to the drawings of FIGS. 8 through 12. The control means is actuated by movement of a control handle to various positions. Control handle 170 is keyed to a control rod which extends downwardly to where it is keyed to an extension shaft 17 6. Control rod 175 is enclosed within a control tube 177 extending between the clamping brackets 33. Means to bias the control handle to a center position is provided by centering springs 180. A centering tube 181 is secured within control tube 177. A pair of centering springs 180, each have one end anchored within the retainer 185 which in turn is keyed to the control rod 175 and turns therewith. The opposite ends of centering springs 180 are received in spring retainers 186 at each end of the centering tube 181 and are anchored by means of pins 187 received on inwardly directed flanges 188 at the inside of control tube 177. It will be noted that the platform member 35 receives the control tube 177 and can pivot thereaibout. The ends of control tube 177 are received within collar portions 34 of the clamp supports 33 as shown. A machine screw 189 through both the clamp 33 and control tube 177 secures them together.

Extension shaft 176 extends downward through an opening in the mounting bracket 42. A brake cam member 190 is keyed to the extension shaft beneath the mounting bracket 42. It is understood that mounting bracket 42 is free to pivot on extension shaft 176 between the brake cam member 190 and the bottom of clamp 33. Extension shaft 176 extends through brake cam member 190- and terminates in an eccentric pin 195. An actuating link member 200 (shown best in enlargements of FIGS. 10 and 11) receives the eccentric pin at one end. The remaining end of actuating link 200 is connected at pin 201 to the top of circular cam 205 which is free to revolve in bushing housing 206 attached to the mounting bracket 42. A second larger actuating link 210, is connected to the bottom of cam 205 at pin 208 which is spaced apart from pin 20 1 on a diameter of cam 205. The outer end of link 210 is journaled on the shaft 50.

A brake for shaft 50 is provided by sheave 220, acting as a brake drum, and partial V-belt 225, acting as a brake band. Sheave 220 is joined to shaft 50 by a key 221. Actuation of the brake is by control rod 175 at a center position, and through the brake cam member 190 to actuating linkage. Brake cam member 190 has a cylindrical barrel shape having a slot 191 which is visible in FIG. 8 and indicated by dashed lines in FIGS. 10 and 11.

C-shaped clevis members 230* have ends inserted and pinned within slot 191 of :brake cam member 190 as indicated in FIGS. 11 and 12. The opposite ends of the clevis members 230 are connected to partial V-belt 225. One end of the V-belt 225 is directly joined at end connector 235 to one clevis member 230. The remaining end of V-belt 225 is connected to the other clevis member 230 at end connector 235 through a turnbuckle adjustment means 238 A detachable axle and wheels (not shown) may be provided so that the machine may be easily transported. Upon being clamped and ready to climb, the wheels are detached. When the machine has descended and ready for transportation to a new pole, the wheels may be re-attached.

In operation, the mechanical climber 10 is first engaged at the bottom of a pole 20. The traction unit handles 88 are thrown to bring the V-belts 73 into bearing against the pole 20. The arms 60 are enclosed about the pole 20 and firmly clamped by manually revolving quills 120 by means of engagement of slots 140 with a hand crank (not shown). Motor 40 is then started, and the machine caused to climb by turning control handle 130 counterclockwise, to the right as shown in FIG. 11. The machine 10 is allowed to climb a few inches up the pole 20 and is stopped by allowing the control handle 130* to return to the center braking position, indicated in FIG. 10. Then the transportation wheels and axle (not shown) may be quickly removed.

The lineman with tools and supplies will take his position on the stand 35 and fasten his safety belt about the vertical frame member 30. He will then turn the control handle 130 to the up position in FIG. 11 counterclockwise and hold it there. With reference to FIG. 11, the handle 130 at this position, moves clevis members 230 closer to sheave 220 by virtue of the eccentric connection within slot 191, causing a loosening of V-belt 225, thus releasing the brake. At the same time, there is rotation of the extension shaft 176 and eccentric pin 195 that moves one end of link 200 downward and to the left, as viewed in FIG. 11. This, in turn, through pin 201, will cause a counterclockwise rotation of the actuating cam 205 in housing 206. This lengthens the distance between the pin 201 and the shaft 50, causing a movement of the mounting bracket 42 in a clockwise direction about the extension shaft 176. As shown by the arrow A of FIG. 11, the V-belt 51 will be tightened about sheave portion 46 of pulley 44 and sheave 48, causing the climber 10 to move in an upward direction. That is, transmission through vertical shaft 50, worm 56, worm gear 58, worm gear shaft 59 and ultimately to V-belts 73. Simultaneously, through transmission V-belts 160 take-up screws 90, 91 and 92 are rotated to clamp arms 60 with rollers 150 and traction V-belts 73 against pole 20. The transmissior means may be adjusted by means of the variable pitch sheaves 70, 130 to correlate travel rate and taper of the pole 20. Preferably, the clamping action will slightly lead the climbing travel, that is, the clamping will be tight against the pole 20 and transmission V-belt 160 will have a slight slippage about variable pitch sheaves 70 130. In this manner, arms 60 clamp tightly about the pole 20 at all 7 points, regardless of the pole taper. The machine 10 will continue climbing the pole, as long as handle is held at the up position.

Upon reaching an obstruction, such as that indicated by wire 25, the machine 10 will be stopped with the uppermost arm 60 just below the obstruction. That is, by release of the control handle 170, centering springs will cause control rod 175 to return to a central brake position. This causes a reversal of the actIon shown in FIG. 11, loosening V-belt 51 about sleeves 46, 48. At the same time, rotation of the brake cam member will position clevis members 230, as shown in FIG. 10, to tighten V-belt 225 about brake sheave 220. This assures that the machine 10 will remain stopped in position on pole 20. While the brake is on, there is no rotation of the worm gear shaft 59 and traction V-belts 73 are motionless. Handle 88 is thrown to retract V-belt 73 from pole 20. A hand crank (not shown) is engaged within notch 140 at the end of quill 120. In this manner the uppermost arm 60 is unclamped. Then, the uppermost arm 60 is free to swing outwardly and away from pole 20, in the manner indicated at FIG. 1. Furthermore, stand 35 also may be swung as an aid in avoiding such obstacles.

Once the uppermost arm 60 is out of the way, the machine 10 may continue upwards until the middle arm 60 encounters obstruction 25. Then the uppermost arm 60 is swung back into position around pole 20, handle 88 thrown to reengage V-belt 73 and manually reclamped. Then the middle arm 60 is disengaged and swung away from the pole. Thus, it is understood that in this manner an obstruction 25 may be passed, since at any one time only two arms 60 are required to hold the machine 10 against the pole 20.

At all times it is required that the lineman observe and adjust pressure on all V-belts 73 to be even and of the right amount. This is accomplished by adjustment of variable pitch sheaves 70, 130.

To descend, the process is reversed. That is, handle 170 is turned (clockwise) as shown in FIG. 12. This again causes the brake to disengage by movement of the clevis members 230 to loosen V-belt 225 about sheave 220. Simultaneously, eccentric pin moves an end of link 200 upward to the right, as viewed in FIG. 12. Cam 205 rotates clockwise within the housing 206. This shortens the distance between pivot 201 and shaft 50, causing bracket 42 to pivot inwardly about extension shaft 176. This, of course, loosens V-belt 51 about sheaves 46, 48. At the same time, the inward movement of pulley 44 brings friction portion 45 into engagement within sheave 47. In this manner, the rotation of shaft 50 is reversed, causing the pole climber 10 to descend the pole.

The present invention may be embodied in other specific forms without departing from the spirit of potential attributes thereof and, accordingly, reference should be made to the appended claims, rather than the foregoing specification, as indicating the scope of the invention.

What is claimed is:

1. A mechanical climber for carrying a worker up and down a pole having an obstruction secured thereto, comprising a load-supporting frame, drive means mounted on said frame, a plurality of supporting means mounted on said frame for independent movements relative thereto between inoperative position to clear sa d obstruction and operative position engaging said pole to support said frame thereon, traction means engageable with said pole and receiving power from said drive means for moving the climber up and down the pole, and manually operable control means for selectively controlling said drive means, whereby said climber may be moved on the pole until a first said supporting means is disposed adjacent the obstruction, stopped to enable movement of such first supporting means to inoperative position, again moved while supported on the pole by the other said supporting means to move said first supporting means past the obstruction, and stopped again to enable movement of said first supporting means back to operative position, with successive such movements carrying the worker past the obstruction.

2. A mechanical climber according to claim 1, for use on a tapered pole, wherein said supporting means includes clamping means operable by said drive means for maintaining driving engagement of said traction means with said pole.

3. In a mechanical climber according to claim 2, normally operative transmission means for connecting said drive means with a said clamping means for each said supporting means and adapted selectively to be rendered inoperative to enable movement of the associated said supporting means between operative and inoperative positions.

4. In a mechanical climber according to claim 1, wherein said control means is movable in one direction from a central position to effect ascent of said climber and in the opposite direction to effect descent thereof, means constraining said control means for movement to said central position, and brake means automatically operable to engage said drive means in response to movement of said control means to central position.

5. A mechanical climber according to claim 1, wherein said plurality of supporting means are three in number, any two thereof sufiicing to support said climber on said pole while the remaining one thereof is at said inoperative position.

6, A mechanical climber according to claim 5, wherein said supporting means include three horizontally disposed arms spaced vertically along said frame and pole, each of said arms at said operative position embracing more than one-half the cross-sectional perimeter of said pole, and each being pivotable on a vertically disposed axis at said frame away from said pole to said inoperative position.

7. A mechanical climber according to claim 6, wherein said supporting means include rollers journaled on said arms for clamping contact against said pole, yet allowing longitudinal travel of said climber therealong.

8. A mechanical climber according to claim 7, wherein each of said arms is of separate lengths connected by cross slides for contraction and expansion of said arms according to the cross-section of said pole, and wherein said supporting means include clamping means on said arms operable by said drive means for maintaining driving engagement of said traction means with said pole.

9. A mechanism climber according to claim 8, wherein said clamping means has an adjustable friction means for coupling said clamping means to said drive means and correlating said clamping means to the taper of said pole and travel rate of said traction means, said friction means providing a slight slippage to ensure that said clamping means are secure about said pole.

10. A mechanical climber according to claim 9, wherein said clamping means are provided by helical screws mounted to drive said arms and said friction means are provided by a variable sheave and friction belt drive keyed to said screws.

References Cited UNITED STATES PATENTS 2,174,525 10/1939 Padernal l82l33 2,654,638 19/1953 Elliot 182-133 2,906,365 9/1959 Howard 182-136 REINALDO I. MACHADO, Primary Examiner US. Cl. X.R. 182-l87 

